1. Field of the Invention
The present invention relates to an exposure device for forming patterns on a surface of a flat-sheet material, including a substrate for an electronic circuit, a glass substrate for an LCD and a glass element substrate for a PDP.
2. Description of the Related Art
Exposure devices for forming circuit patterns onto a plane substrate used to be classified into contact and non-contact types. Contact type exposure devices bring a transfer mask into contact with a substrate (or an object), and non-contact type devices do not put them in contact. However, different type exposure devices, which form circuit patterns onto a substrate without using a transfer mask by directly irradiating exposure light on the substrate, have been introduced (see Japanese Unexamined Patent Application Publications 2006-113413 and 2006-343684). Devices of this maskless type are increasingly in demand due to their excellent maintenance properties.
Such a maskless type exposure device is configured to receive exposure data on transfer patterns and to control exposure light by using spatial light modulators (or digital micro-mirror devices (DMDs)), based on the received data, so that it achieves the maskless operation.
The exposure device of JP A 2006-113413 or JP A 2006-343684 uses a shutter device and DMDs and operates them in sync with each other, thereby controlling exposure light necessary for forming patterns. In this device, each DMD is constituted of multiple micro-mirrors, and their orientations are changed whereby the exposure light is controlled. However, changing the orientations involves a considerable time. Accordingly, the exposure device needs to halt the exposure operation while the orientations of the micro-mirrors are in the course of changing, for example, after an object is fed. Thus, this period is prone to hinder the enhancement of the exposure speed. In other words, it can be the production bottleneck.
In order to improve the production capacity, various approaches to control exposure light efficiently have been employed. One of them is to use a photosensitive material having an improved sensitivity to g, h and i lines and a UV lamp for emitting light of those wavelengths. Consequently, the reaction speed of photosensitive material is increased. However, no matter how fast the reaction speed is, the time period required to change the orientations of the micro-mirrors is still critical in improving the efficiency of the exposure operation.
Taking the above disadvantage into account, the present invention has been conceived. An object of the present invention is to provide an exposure device which can conduct an exposure process efficiently. An additional object of the present invention is to present an exposure device which achieves a short spatial light modulation time.